Doping and strain modulation of the electronic, optical and photocatalytic properties of the GaN/C2N heterostructure.

Abstract

The electronic, optical and photocatalytic properties of GaN/C2N van der Waals heterostructures are investigated using the first-principles theory, and effective regulation through element doping or strain is achieved further. The results show that the GaN/C2N heterostructure exhibits a type-II band alignment with an indirect band gap of 2.25 eV, which benefits photocatalytic water splitting. In this study, both type-I and type-II band alignments can be obtained through doping or strain modulation. Doping with P or As atoms reduces the band gap of the GaN/C2N heterostructure and transforms it to a type-I direct bandgap semiconductor, which makes the doped GaN/C2N heterostructure more suitable for optoelectronic devices. In addition, the GaN/C2N heterostructure retains type-II band alignment and has a decreased band gap under tensile strain (0 to +4%), which is more favorable for photocatalytic water splitting. Compressive strain (0 to -4%) converts the type-II band alignment to type-I, resulting in a wider light absorption range, making the GaN/C2N heterostructure more suitable for optoelectronic devices. These theoretical results are helpful for the design of GaN/C2N vdW heterostructures in the fields of optoelectronic devices and photocatalysts.